I have a Singer 201 that started making a "plink" noise. I finally tracked it down after pulling the bobbin and rotary hook. When the bobbin case/rotary hook spins and the needle comes to the down position, the needle gets hit by a tab on the rotary hook.
The picture below shows the hook sliding along after being hit. When the tab goes around, the needle pops back. Sorry for the incorrect terminology.
Does anyone know if this can be fixed? Is it a timing problem? I've done an extensive internet search, but can't find anything similar.